Dynamics of the Galionella spp. and Leptothrix spp. Communities of Polluted Mine Drainage Water in Slovinky and Markušovce (Slovakia)

Abstract

Tailings ponds Slovinky and Markušovce (Slovakia) belong to the group of high-risk areas threatening human health and the environment due to the high concentrations of potentially toxic elements. The aim of this study was to identify iron bacteria living in these extreme environments and to assess the impact of selected physicochemical parameters of drainage water, flowing from tailings ponds, on the dynamics of their population. The material deposited on the Slovinky and Markušovce tailings pond showed a circumneutral pH. The values of electrical conductivity and total dissolved solids were significantly higher in drainage water in Slovinky compared to Markušovce. The concentration of total iron was notably higher in drainage water in Markušovce than in Slovinky. Direct microscopic observations showed the presence of iron-oxidizing bacteria as Gallionella spp. and Leptothix spp. exhibiting significant seasonal changes in their prevalence. The differences in the environmental characteristics of drainage waters did not affect the dynamics of iron-oxidizing bacteria populations, but cultivable heterotrophic bacterial community showed significantly lower abundance in Markušovce drainage water. The findings contribute to the understanding of bacterial diversity in neutral mine drainage waters and demonstrate an important role of environmental factors in shaping the microbial population in mine environments.